1. Field of the Invention
The invention relates to a method and apparatus for processing food. In another aspect, this invention relates to a method and apparatus for the automated cutting of foodstuffs into portions of predetermined sizes. In still another aspect, this invention relates to a method and apparatus for the automated cutting of fish fillets, chicken, meat or other foodstuffs of irregular cross-section into portions of predetermined sizes.
2. Description of the Related Art
In the production of packaged frozen foods such as meat, chicken or fish products, it is important that the weight of the portions be controlled as accurately as possible, otherwise the weights will vary at the time of the filling of the packages resulting in certain disadvantages. For example, underweight portions of incorrect weight have to be rejected leading to significant losses of fish or meat material while overweight portions have to be adjusted to the correct weight, which increases the cost of processing and packaging.
Fish, chicken and meat portions of uniform weight are also desired by restaurants to ensure that customers receive servings which are neither too slight nor too generous. For example, a restaurant may prefer to serve its patrons 6 ounce or 8 ounce portions of fish and will pay more for fish portions which are within a given tolerance of the desired weight.
When whole fish is commercially processed, the fish is typically sent to a filleting machine which cuts the fish along the backbone to produce two elongated portions or "fillets." The fillets are further divided into portions of predetermined size by making cuts transverse to their long axis, such cuts being spaced at distances which depend on the cross-section of the fillet.
Prior art methods for estimating and cutting such fillet portions to a predetermined size include both manual and automatic methods.
Manual methods of cutting fillet portions generally consist of manually estimating the portion of a fish fillet necessary to provide the desired weight, and then manually cutting the fillet. The cut fillet portions are then weighed to determine if they were within the tolerance desired for a particular use. Manual estimating and cutting suffers from being relatively slow and labor-intensive, and even the most skilled laborer cannot always produce accurate portions.
U.S. Pat. No. 4,557,019, issued Dec. 10, 1985, to Van Devanter et al. and U.S. Pat. No. 4,875,254, issued Oct. 24, 1989, to Rudy et al. both disclose apparatus for automatically portioning fish fillets, in which fillets are applied to a conveyor belt, passed through an electronic image scanning system, then cut into a plurality of portions by a cutting mechanism. The electronic image scanning system detects and scans the shape of the fillet, computes the weight of the fillet, and then activates the cutting mechanism to make the desired cuts.
The Van Devanter et al. cutting mechanism is a rotary saw which is passed across the fillet in a direction slightly skewed from transverse to prevent the saw blade from displacing the fillet longitudinally while cutting. However, the high mass and lengthy travel of the rotary saw limits repetition rate of cuts or requires large and expensive drive and support components to achieve adequate repetition rate. Thus while the apparatus may be suitable for limited commercial production, without an adequate repetition rate, it is not possible to integrate the Van Devanter et al. apparatus into an automatic filleting line. It is also well known that the apparatus does not ensure a complete division or separation of the fillet portions reliably because it is difficult to operate the saw such that it cuts through the fillet without also cutting the conveyor belt. Furthermore, the transverse motion of the saw tends to displace the fillet from the position in which it was measured on the conveyor, upsetting precision of subsequent cuts. Finally, the saw kerf can remove a significant amount of flesh which is wasted.
Rudy et al. utilizes as the cutting mechanism a high pressure water-knife system. Unfortunately, the water-knife system is very expensive and generates a high level of audible noise which is disruptive in a production environment.
Since both prior art systems utilize a projected light pattern and electronic camera to measure fillet volume, they are subject to problems created by spurious reflections of light due to specularity such as that created when the conveyor belt is wet.
Therefore a need exists in the art for an apparatus and method for automatically portioning fish, chicken, meats and other foodstuffs into portions of predetermined size, without the prior art deficiencies.